JP3189721B2 - Estimation method of thickness of tapered steel plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating the thickness of a tapered steel sheet which is effective when manufacturing a tapered steel sheet whose thickness gradually changes in the longitudinal direction.

[0002]

2. Description of the Related Art When manufacturing a tapered steel sheet whose thickness gradually changes in the longitudinal direction, a thickness distribution, that is, a taper gradient is mainly given by a rolling method. When the rolling method is used, a steel sheet rolled so as to have a predetermined taper gradient is first measured for a thickness distribution, and then subjected to a refining process such as cutting or straightening to be a final product.

[0003] As a method for refining this tapered steel sheet, for example, a method disclosed in Japanese Patent Application Laid-Open No. 7-185604 discloses a method for measuring the thickness distribution of a tapered steel sheet in the longitudinal direction after rolling. The sampling position of a taper steel plate having a predetermined size is determined. This method is intended to change a cutting point in order to solve a problem caused by poor thickness control accuracy in rolling.

[0004]

However, in the above prior art, although the importance of measuring the thickness distribution of a tapered steel sheet after rolling is shown, the method of measuring the thickness distribution is not mentioned at all. Not. In a tapered steel plate, unlike a normal flat steel plate, there is a gradient, so that a large error occurs when measuring the plate thickness, which is a serious problem in actual production.

More specifically, when measuring the thickness of a steel sheet, a method of irradiating the steel sheet with X-rays or γ-rays and detecting the amount of transmitted light is usually used. It is common to perform a moving average process to remove the effects. The moving average process outputs the average of the measured values during the past α sec from that point in time as the measured value at a certain point in time. The larger the is, the more the error occurs in the measured value.

If the rate of change of the thickness of a sheet is constant within the same sheet, the tendency of the error of the measured value of the sheet thickness is constant to some extent.
When the rate of change of the plate thickness changes in the same plate, that is, in the case of a tapered steel plate having a plurality of taper gradients in the same plate, it is extremely difficult to estimate the thickness measurement error near the change point of the taper gradient.

If an attempt is made to refine a steel sheet based on a thickness measurement value including such a large number of errors, for example, the thickness of the sheet after cutting is out of a predetermined standard and the sheet is rejected in the inspection process. Or, if you try to perform the correction with Laura Leveler, the load of the straightening machine is too small or too large,
Insufficient straightening effect is obtained or the straightener is damaged.

It is an object of the present invention to provide a method for estimating the thickness of a tapered steel sheet which can minimize such errors in the accuracy of measuring the thickness of the tapered steel sheet and minimize the occurrence of problems in the subsequent refining process. And

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a tapered steel sheet whose thickness gradually changes in a longitudinal direction, by continuously measuring the thickness of the tapered steel plate, and measuring the obtained measurement value by a thickness gauge. The actual passing speed of the position, the target or actual taper gradient, that is, the rate of change of the plate thickness, the moving average time of measurement, and
A method for estimating the thickness of a tapered steel plate, wherein the measurement value is corrected based on the measured response delay time .

From another aspect, the present invention provides a method of manufacturing a tapered steel plate having a plurality of taper gradients whose thickness gradually changes in the longitudinal direction, by continuously measuring the thickness, The actual threading speed at the thickness gauge position, the target or actual taper gradient, that is, the rate of change of the thickness, and the measurement
Correcting the measured value based on the moving average time and the response delay time of the measurement, the change point of the taper slope at the intersection of the extrapolation line of the corrected measured values of both slopes near the change point of the slope This is a method for estimating the thickness of a tapered steel plate.

As described above, according to one aspect of the present invention, the thickness distribution of a tapered steel plate whose thickness gradually changes in the longitudinal direction is continuously measured, and the thickness of the plate is determined based on the measured value. In performing refining, the actual passing speed of the thickness gauge position, the target or actual taper gradient , the moving average time of the measurement,
A method for manufacturing a tapered steel sheet, comprising correcting a sheet thickness measurement result based on a measurement delay time .

According to another aspect of the present invention, when measuring the thickness distribution of a tapered steel plate having a plurality of taper gradients, the thickness measurement results near the change point of the taper gradient are determined as described above. The tapered steel plate manufacturing method is characterized in that the tapered slope is changed at the intersection of each extrapolation line of the measured values before and after the change point obtained by the correction.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the contents of the present invention will be described with respect to a method for estimating the thickness distribution of a steel plate having a constant taper gradient. In the following, a thickness gauge is shown as an example of a non-contact thickness gauge using X-rays or γ-rays, but the same applies to a contact thickness gauge.

For example, in the case of a non-contact thickness gauge using X-rays or γ-rays, an error due to statistical noise increases when an instantaneous value of measurement is output as a result. The result of the application is output as a measured value. That is, the average value of several preceding measurement values within the average travel time from one measurement point is determined as a true value.

[0015] However, considering the steel sheet thickness is increased gradually as measured, as shown in FIG. 1, the moving average process, the thickness measurement t _o is a small one than the true value t _a Become. The difference between the sheet thickness measurement value and the true value naturally increases as the moving average time of the thickness gauge increases,
In addition, the larger the passing speed at the position of the thickness gauge and the greater the rate of change of the thickness, the larger the value.

However, on the other hand, this difference can be predicted if the sheet thickness change rate and the sheet passing speed at the position of the sheet thickness gauge can be known. By multiplying the speed, the thickness measurement value can be corrected. FIG. 2 shows a configuration example of an apparatus for performing the measurement value correction method according to the present invention.

In the example shown in FIG. 2, the change rate of the thickness of the tapered steel sheet a uses the target change rate of the target thickness in the rolling process or the actual change rate of the thickness. The value calculated by the speed calculator c from the number of rotations of the transport roll b and the diameter of the transport roll immediately adjacent to the thickness gauge is used. Since the moving average time of the thickness gauge d is known, an error of the measured thickness value can be estimated by the estimated thickness calculating device e from these values.

Specifically, the true plate thickness is estimated according to the following equation (1). _{t e = t o + (Δt} / Δl) × (v × T 1/2 + T 2) ··· (1) (1) In formula, t _e is the estimate of the true sheet thickness, t _o is the thickness gauge (Δt / Δl) is the target or actual thickness change rate, that is, the taper gradient, v is the passing speed at the thickness gauge position, T ₁ is the moving average time, and T ₂ is the measurement response. The delay time. Although the largest cause of the thickness measurement error of the tapered steel plate is due to the moving average process, the measurement delay is also a cause of the error.

Next, a method for estimating the thickness distribution of a tapered steel plate having a plurality of taper gradients in the same plate will be described.
For example, the thickness distribution near the change point of the taper gradient as shown in FIG. 3A is measured by a thickness gauge as shown in FIG. 3B. In FIG. 3 (b), t _a is the true sheet thickness, t _o is the measured thickness of the thickness gauge.

Here, if the change point of the taper gradient can be accurately known, the true thickness distribution can be measured from the measured value of the thickness gauge in the same manner as in the above-described method, but the change point of the taper gradient can be accurately determined. If the thickness distribution cannot be measured, it cannot be known accurately, and contradictions arise here. In order to solve this problem, before the change in the taper slope measured by the thickness gauge and after the change in the taper slope has settled, that is, from the measured value of the sheet thickness at the second taper slope, the slope change point The thickness distribution in the vicinity may be estimated.

The outline of this method will be described with reference to FIG.
First, as shown in FIG. 4 (a), the portion where the gradient of the thickness gauge measurement value is constant is extrapolated to the vicinity of the gradient change point, and the true thickness is estimated from each measured gradient by using equation (1). Do. FIG.
(b) shows the result of this estimation. Here, the estimated thickness distribution t
The intersection of the two taper gradients shown at point A in _e can be estimated as a change in the taper gradient.

[0022]

Next, the specific operation and effect of the present invention will be described with reference to examples. In each of the examples, the taper gradient was a target value, and the actual threading speed at the thickness gauge position was 150 to 1500 mm / sec. The correction of the measured value of the plate thickness was performed according to the above-mentioned equation (1). Where T
₂ = 0.01 sec.

First, as a first example, FIG. 5 shows a result of estimating the thickness distribution of a tapered steel sheet when the method of the present invention is applied under the conditions shown in Table 1. The line a in FIG. 5 is the true thickness, and the line o is the conventional method, that is, without applying the method of the present invention.
The measurement result of the thickness is assumed to be the actual thickness distribution as it is, and a line e is an estimated value of the thickness distribution to which the method of the present invention is applied. According to this, the difference between the line o and the line a, that is, the measurement error of the conventional method is about 0.3 mm, whereas the difference between the line e and the line a, that is, the estimation error by the method of the present invention is about 0.1 mm.
mm.

As a second example, similar results when the method of the present invention is applied under the conditions shown in Table 2 are shown in FIG.
Shown in Lines a, o, and e show the true thickness, the thickness by the conventional method, and the thickness when the method of the present invention is applied, respectively, as in FIG. According to this, the conventional method has a measurement error of about 0.9 mm at the maximum and the change point of the thickness gradient is very unclear, whereas the estimation error of the thickness is reduced by the method of the present invention. There is a maximum of about 0.1 mm, and it is possible to accurately know the change in the thickness gradient.

Further, as a third example, FIG. 7 shows a similar result when the method of the present invention is applied under the conditions shown in Table 3. According to this, the conventional method has a maximum of about 0.6 mm
In the method of the present invention, the estimation error of the plate thickness is about 0.1 mm at the maximum, and the change point of the plate thickness gradient is also accurate. I can know.

[0026]

[Table 1]

[0027]

[Table 3]

[0028]

As described above, according to the method of the present invention, it is possible to accurately estimate the thickness distribution of a tapered steel plate whose thickness gradually changes in the longitudinal direction. For example, when the method according to the present invention is applied to the production of a tapered steel plate having a range as shown in Table 3, rejection due to deviation from dimensions can be reduced by 50% or more compared to the conventional method, and the efficiency of straightening can be further reduced. Also improved by about 10%.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a thickness measurement error in a conventional method.

FIG. 2 is a schematic explanatory view showing an example of an apparatus configuration for implementing the method of the present invention.

FIG. 3 (a) is a schematic sectional view of a tapered steel plate having two taper gradients, and FIG. 3 (b) is an explanatory diagram of a thickness measurement error of such a tapered steel plate in a conventional method. .

FIGS. 4 (a) and 4 (b) are explanatory diagrams of the operation and effect of the present invention.

FIG. 5 is an explanatory diagram showing a difference between a result of estimating a sheet thickness by a method of the present invention and a result of measuring a sheet thickness by a conventional method in an example of the present invention.

FIG. 6 is an explanatory diagram showing a difference between a result of estimating a sheet thickness by a method of the present invention and a result of measuring a sheet thickness by a conventional method in an example of the present invention.

FIG. 7 is an explanatory diagram showing a difference between a result of estimating a thickness by a method of the present invention and a result of measuring a thickness by a conventional method in an example of the present invention.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI B21C 51/00 B21B 37/14 BBJ (58) Field surveyed (Int.Cl. ⁷ , DB name) B21B 1/38 B21B 37/00 B21C 51 / 00 G01N 23/00-23/227 G01B 15/00-21/32

Claims (2)

(57) [Claims] In producing a tapered steel sheet whose thickness gradually changes in the longitudinal direction, the thickness is continuously measured, and the obtained measured value is used as an actual passing speed at a thickness gauge position,
Target or actual taper slope and moving average time for measurement
And estimating the measured value based on the response delay time of the measurement. 2. In manufacturing a tapered steel sheet having a plurality of taper gradients whose thickness gradually changes in the longitudinal direction, continuously measuring the thickness and measuring the obtained measurement value at the position of the thickness gauge. Actual threading speed and target or actual taper slope
Correcting the measured value based on the moving average time of the measurement, and the response delay time of the measurement, and extrapolating the corrected measured values of the two gradients near the gradient change point. A method for estimating the thickness of a tapered steel plate, wherein the point of change of the taper gradient is defined as the point of intersection.